In general, making a weld or series of welds for joining together the two ends of optical fibers requires a great length of fiber. Once the weld is completed, it is necessary to absorb the excess length without it resulting in too small radius bends.
Junction boxes are known, notably through U.S. Pat. No. 4,516,830, comprising two end anchor parts and one central mandrel receiving the excess length of fiber. The fibers are welded, then wound round the mandrel and the welds are secured to the mandrel. In this way the fibers are totally secured, which renders them liable to snap upon the slightest tension being exerted. Moreover, the device calls for filling with a viscous and/or water-repellent product for protecting the fibers against moisture.
The purpose of this invention is to submit a junction and/or repair box provided with slack chambers for receiving the excess lengths of fiber. The welds are secured to the mandrel but the fibers are still free to move. This junction box furthermore is effectively watertight without mandatorily having recourse to fill products.